Escapement device



Dec. 8, 1936.

EIBERT ESCAPEMENT DEVICE 2 Shets-Sheet 1 Filed Deq 22', 1934 v INVENTOR I FRITZ -E/BERT' BY @(xM ATTORNEY Dec. 8, 1936. ElBERT 2,063,371

ESCAPEMENT DEVICE Filed Dec. 22, 1934 2 Sheets-Sheet 2 INVENTOR FR TZ 575 ER T ATTORNEY Patented Dec. 8, 1936 UNITED STATES PATENT OFFICE ESCAPEMENT DEVICE Application December 22, 1934, Serial No. 758,715

9 Claims.

The present invention relates to carriage escapements, and more particularly, toan improved escapement device for a typewriter carriage.

In prior typewriters, the operating speed has been limited by the fact that the pawl carrier of the escapement device did not return quickly enough to its normal or rest position after the impression of a type. To speed up the return movement of the pawl carrier, it has been suggested to use a stronger return spring for the pawl carrier. It was found, however, that a strong spring was objectionable and considerably increased the forces to be overcome by the depression of the key lever with the result that high writing speeds were impossible. Although many attempts were made to overcome the disadvantages, none as far as I am aware, were wholly satisfactory and successful in practical 2O operation.

I have discovered that it is possible to eliminate the shortcomings of prior escapement devices in a remarkably simple manner.

It is an object of the present invention to provide an improved paper carriage escapement. which is simple in construction and which is quick and efiicient in operation.

It is another object of the present invention to provide an escapement device for typewriters which operates reliably at practically any writing speed.

A further object of the invention is the provision of an escapement which does not put any appreciable load on the key levers of the typewriter and which derives the energy for its operation from the main ratchet wheel of the typewriter which is powered by a strong carriage spring.

The invention also contemplates a resilient auxiliary member or pawl which can be attached to conventional pawl carriers without changing the conventional co-operating parts of the escapement and which effects the improvement of the reliability and the operating speed of conventional escapements.

Other and further objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

Fig. 1 illustrates an embodiment of my invention including a vertical elevation, partly in section, of the key action of a typewriter;

Fig. 2 is a fragmentary plan of the escapement device shown in Fig. 1 and embodying my invention;

Fig. 3 illustrates a side elevational View of the escapement device;

Fig. 4 depicts a similar view showing the position of the pawl carrier when one of the keys of the typewriter is depressed;

Fig. 5 shows the escapement in the position when one of the ratchet wheel teeth engages the retaining pawl;

Fig. 6 is a fragmentary side elevational view of a modified embodiment of my invention; and

Fig. 7 illustrates a side elevational View, partly fragmentary, of another modified embodiment of my invention.

According to the principles of my invention, I provide on a suitable part of the typewriter, preferably on the pawl carrier, a resilient auxiliary member or pawl. In the preferred embodiment of my invention, this resilient auxiliary member or pawl has an angular surface at one end and is fastened to the carrier at the other end. When one of the keys of the typewriter is depressed and the pawl carrier is actuated, the angular surface at the end of this resilient auxiliary member or pawl will enter one of the spaces between the adjacent teeth of the ratchet or rack. I have found that the resiliency of the auxiliary pawl has to be such as to be overcome by a displacement of the ratchet wheel teeth under the influence of the carriage spring. During their movement the teeth of the ratchet wheel will slide along the angular surface of the auxiliary member or pawl, will deform same and will accumulate a certain amount of energy therein. When the depressed key is released, the energy accumulated or stored in the auxiliary pawl will be liberated and will be utilized for quickly and automatically returning the pawl carrier and the associated pawls to their normal position of rest.

Referring now more particularly to Figs. 1 to 5 in the drawings, a ratchet wheel it having teeth Z is rotatably mounted on axle m. The ratchet wheel is powered by a main spring which is operatively associated with a rack s and gear 1 or by any other conventional means. A pawl carrier a bearing a displacement pawl 12 and a pivotally mounted retaining pawl c is arranged in a customary manner between bearings h and 2'. On the pawl carrier a, I provide the auxiliary pawl d Which is positioned in a tangential direction to the circumference of the ratchet wheel. I prefer to make the auxiliary pawl in the form of a fiat, resilient spring having at the end thereof an angular surface p which is adapted to enter the spaces between the teeth. The other end of the resilient auxiliary pawl is secured to the pawl carrier, for example, by screws 11: or some other appropriate means.

The left side of Fig. 1 shows a conventional key action comprising key lever A which is connected by link B to type lever C. The other end of the key lever A co-operates through bell crank lever E and link F with the pawl carrier a.

From the foregoing description, the operation of my improved escapement will be apparent tothose skilled in the art. In the normal or rest position illustrated in Figs. 1 to 3, the retaining pawl 0 will be engaged with one of the teeth of the ratchet wheel and consequently will prevent movement of the said wheel under the influence of the carriage spring. When key lever A is depressed, the type lever C will be actuated through link B and will strike against platen- D. At the same time, the pawl carrier a will be actuated by bell crank lever E and link F and will be displaced'to the position indicated in Fig. 4. The retaining pawl 0 will release the ratchet wheel which under the influence of the main carriage spring will move forward in the direction of the arrow until it abuts the working surface of the displacement pawl b set back a little in relation to the working surface of the retaining pawl. Simultaneously with the displacement of the pawl carrier, the auxiliary pawl d will be displaced and the angular surface 1) at its end will enter the space between two consecutive teeth of the ratchet wheel and will engage one of the teeth. The angular surface 1) on the auxiliary pawl d will slide along the surface of the teeth during the displacement of the ratchet wheel under the influence of the main spring whereby the resilient auxiliary pawl will be deformed or bent and energy will be stored up expended in the displacement of the wheel (Fig. 5) Assoon as the depressed key lever and the pawl carrier are released, the auxiliary pawl will be straightened out due to its resiliency and will. quickly return the pawl carrier (1 and the pawls associated therewith to their normal position depicted in Fig. 2 or 3.

It is to be observed that my resilient auxiliary pawl effects considerable advantages. The pawl carrier will be instantaneously returned to its normal or rest position by means of the energy .storedin the resilient auxiliary pawl without the use of the conventional return spring of the carrier. which necessarily increases the resistance to be overcome by the key levers. The elimination of the carrier return spring reduces the resistance to be overcome during the depression of a key quite considerably, assures a very easy and smooth touch, and permits completely satisfactory and reliable operation of the typewriter at all writing speeds.

A modified embodiment of my invention is illustrated in Fig. 6. In this embodiment, the auxiliary pawl d-l proper is not made of resilient material but is pivoted in o and is provided with a return spring 6. This spring is compressed when angular surface p-I of the auxiliary pawl'dl is displaced by the moving teeth I of the ratchet wheel k. In view of the similarity of construction of my modified escapement with the escapement described hereinabove, the description will not be repeated as similar reference characters have been used to denote parts corresponding to those illustrated in Figs. 1 to 5. The operation of my modified escapement is similar to the one describedhereinabove and will be readily understood from Fig. 6 by those skilled in the art.

An important advantage of my invention is that it can be easily embodied in practically any standard typewriter of conventional design without changing the construction either of the ratchet wheel or of the pawl carrier or of the retaining and displacement pawl associated therewith or of any of the other standard parts. It is only necessary to add my resilient auxiliary pawl to the pawl carrier whereby all of the benefits of my invention are obtained.

It will be noted that instead of mounting my resilient auxiliary pawl on the pawl carrier, it may be mounted on some other suitable part of the typewriter in the proximity of the escapement. A modified embodiment of this type is illustrated in Fig. 7.

This embodiment appears to be much similar to the one depicted in Fig. 6 with the difference that instead of being mounted om the pawl car rier, the auxiliary resilient pawl d2 is: pivoted in v on-a=- suitable stationary part of the typewriter in the proximity of the escapement. A flat spring a is rigidly connected to the auxiliary pawlxd-l at oneend and is adapted to be engaged by a pint on the pawl carrierat the other end. The auxiliary pawl (1-2 is provided with an angular surface 40-2.

The operation of this modified embodiment of my-invention will be readily understood by those When depressing a key enter one of the intervals between the -ratchet wheel teeth, 1c. By the subsequent displacement of the releasedratchet wheel, toothk will engage.

angular surface p2 and will return d2- at the same time deforming or bending spring us When thexdepressed. key is. released, spring a will be straightened. out and will return the pawl carrier andthe associated pawls into their initial position of rest. I

Although I have described the principles of my invention in connection with two practical embodiments thereof, many-variations and modifications are possible and will suggest themselves to those skilled in the artwithout departing from the principles of the invention. All of these variations and modifications are to be considered as being within the true spiritandscope of" my invention. as described in the present-specification and as definedinthe appended claims.

I claim: I

1. In an escapement device for a typewriter, the combination which comprises a spring'powered'ratchet wheel, apawl carrier with associated pawls capable-of actuation by a key of said.type-- writer to permit intermittent movement of said ratchet wheel, resilient means between said.

ratchet wheel and saidpawl carrier adapated to be deformed and to absorb energyduringand from the movement of said ratchet wheel andto resilient means between said rack and said pawl carrier adapted to be deformed and to storei'en 75",

ergy during and from the movement of said rack and to release said energy in returning said pawl carrier to its normal position of rest when said actuated key is released.

3. In an escapement device for a typewriter, the combination which comprises a spring powered ratchet wheel having teeth, a pawl carrier with associated pawls capable of actuation by a key of said typewriter to permit intermittent movement of said ratchet wheel, a resiliently displaceable member between said ratchet wheel and said carrier adapted to be displaced and to store energy during and from the movement of said ratchet wheel teeth and to release said energy in returning said pawl carrier to its normal position of rest when said actuated key is released.

4. In an escapement device for a typewriter, the combination which comprises a spring powered ratchet wheel having teeth, a pawl carrier and pawls associated therewith capable of actuation by a key of said typewriter to permit intermittent movement of said ratchet wheel, a resilient member mounted on said pawl carrier and adapted to be deformed and to absorb energy during and from the movement of said ratchet wheel whereby said energy will be released in returning said pawl carrier to its normal position of rest when said actuated key is released.

5. In an escapement device for a typewriter, the combination which comprises a spring powered ratchet wheel having teeth, a pawl carrier with associated pawls capable of actuation by a key of said typewriter to permit intermittent movement of said ratchet wheel, a resilient fiat spring mounted on said carrier at one end and'adapted to enter the intervals of the ratchet wheel teeth at its other end whereby said resilient flat spring will be deformed and bent during and by the movement of the ratchet wheel teeth and due to its resiliency will be straightened out and will return said pawl carrier quickly to its normal position of rest when said actuated key is released.

6. In an es'capement device for a typewriter, the combination which comprises a spring powered ratchet wheel having teeth, a pawl carrier and pawls associated therewith capable of actuation by a key of said typewriter to permit intermittent movement of said ratchet wheel, a resilient flat spring having one of its ends mounted on said carrier and having its other end bent up to form an angular surface entering the spaces between the ratchet wheel teeth whereby said flat spring will be engaged and deformed during and by the movement of said ratchet wheel after said carrier has been actuated and said spring due to its resiliency will return said pawl carrier to its normal position of rest when said actuated key is released.

7. In an escapement device for a typewriter, the combination which comprises a spring powered ratchet wheel having teeth, a pawl carrier and pawls associated therewith capable of actuation by a key of said typewriter to permit intermittent movement of said ratchet wheel, a resilient auxiliary pawl mounted on said carrier at one end tangentially to the circumference of said ratchet wheel and having an angular surface at its other end adapted to enter the intervals between said ratchet wheel teeth when said pawl carrier is actuated whereby said resilient auxiliary pawl will be engaged and deformed during and by the movement of said ratchet wheel and said auxiliary pawl will return said pawl carrier to its normal position of rest when said actuated key is released.

8. In an escapement device for a typewriter, the combination which comprises a spring powered ratchet wheel having teeth, a pawl carrier and pawls associated therewith capable of actuation by a key of said typewriter to permit intermittent movement of said ratchet wheel, a pivoted and resiliently mounted auxiliary pawl on said pawl carrier having a surface at one end adapted to enter in between the teeth of said ratchet wheel when said carrier is actuated, whereby the end of said auxiliary pawl will be engaged and said pawl will be turned on said pivot during and by the movement of said ratchet wheel and said auxiliary pawl will regain its original position and will return the pawl carrier to its normal position of rest when said actuated key is released.

9. In an escapement device for a typewriter, the combination which comprises a spring powered ratchet wheel having teeth, a pawl carrier and pawls associated therewith capable of actuation by a key of said typewriter to permit intermittent movement of said ratchet wheel, a lever pivoted on said carrier having a spring at one end and an angular surface at its other end, said angular surface being adapted to enter in between the teeth of said ratchet wheel when said carrier is actuated whereby said lever will be displaced and said spring will be deformed during and by the movement of said ratchet wheel and said lever will regain its original position and will return the pawl carrier to its normal position of rest when said actuated key is released.

FRITZ EIBERT. 

